Ajax & CI3

My main concern is not to clutter up the view with all sorts of bits of script etc... but with an event driven thing like AJAX I can't see any way to avoid it.

You should be able to put most of the script into .js files and load them into your views with script tags (or use an assets library to load them). More often than not, you'll be able to boil down most of your site into a handful of page types which need specific sets of scripts. At that point, you can usually load a set of scripts for the current page type and then add a couple of lines of script to configure the scripts for the current page, if needed.

Bonfire

Practical CodeIgniter 3
CodeIgniter Testing Guide